It's sweeping the world of business. You give your product or service away for free and make money selling ads. TrendWatchers.com analyzes the phenomenon in their latest brief, calling it "Free Love." (Chris Anderson also has this piece on "freeconomics" in The Economist.)Ever since the first days of IM, Napster and video game emulators in the late '90s it was pretty clear that the way digital products were valued was in for a drastic change. That part of the trend is old news.Both pieces miss something truly new though: The Big Sister Brothel is free and subsidized by online advertising. "Free love" indeed. Emotional fulfillment not included.